Compounding ingredients stearic acid

The principal mbbers, eg, natural, SBR, or polybutadiene, being unsaturated hydrocarbons, are subjected to sulfur vulcanization, and this process requires certain ingredients in the mbber compound, besides the sulfur, eg, accelerator, zinc oxide, and stearic acid. Accelerators are catalysts that accelerate the cross-linking reaction so that reaction time drops from many hours to perhaps 20—30 min at about 130°C. There are a large number of such accelerators, mainly organic compounds, but the most popular are of the thiol or disulfide type. Zinc oxide is required to activate the accelerator by forming zinc salts. Stearic acid, or another fatty acid, helps to solubilize the zinc compounds. 

A compounding ingredient that enables an accelerator to exercise its maximum effect. Inorganic activators are metallic oxides (such as zinc, lead and magnesium oxides) and organic activators are long-chain saturated fatty acids, e.g., stearic and oleic. 

C, depending on the blend ratio. The blends were compounded in a two-roll laboratory miU, with three cure systems, the mixtures and their ratios being blend (100.0), zinc oxide (5.0), stearic acid (1.5), styrenated phenol (1.0), diben-zothiazyl disulfide (0.8, only in the sulfur and the mixed cure systems) DCP (4.0, 40% active ingredient, only in the DCP and the mixed cure systems) and sulfur (2.5, only in the sulfur and the mixed cure systems). The compounded blends were molded to optimum cure in a steam-heated hydraulic press at 160°C to obtain the test samples. The blends containing 0 wt% EVAc could not be fully cured with sulfur. The samples were irradiated with a Co-60 source at a dose rate of 3.21 kGy/h to doses of 100-500 kGy. 

Alginic acid s-Amyl acetate Bayberry (Myrica cerifera) wax Beeswax s-Butyl acetate C12-18 acid triglyceride Carboxymethylcellulose sodium Casein Cellulose acetate Ethylene/MA copolymer Milk protein Perchloroethylene Polyvinyl alcohol Sodium silicate Starch Styrene/MA copolymer Tristearin sizing compounds Calcium bromide Sodium borate sizing ingredient, paper Dodecenylsuccinic anhydride Rosin Sodium stearate Stearic acid sizing paper Dextrin... 

Taking into account the statements above it is to be concluded that the stearic acid is an ingredient for mbber compounds or blends of multifunctional effect. The stearic acid is ... 

In conclusion, it should be summarized that stearie is an important ingredient for rubber eompounds and blends. For almost 100 years it has eontinued to be the unique dispergator for carbon black filled rubber compounds. On the basis of measurements of the rheologieal properties of the rubber compounds and depending on the stearic acid in them, speeifying the optimal amount of the dispergator for the carbon black contained in the rubber... 

The two most common activators used with sulfur cure systems are zinc oxide and stearic acid. Virtually all sulfur-cured rubber compounds contain zinc oxide and stearic acid. This means that thousands upon thousands of rubber recipes have these two ingredients. This makes them the most commonly used rubber compounding ingredients, appearing in more different recipes than any other ingredient. 

Rubber-grade "stearic acid is usually a mixture of stearic acid (a Cl8 saturated fatty acid) and palmitic acid (a Cl6 saturated fatty acid) usually with a very small amount of oleic acid (a Cl8 fatty acid with one unsaturated site per molecule). Just as zinc oxide is ubiquitous in rubber recipes, so is rubber-grade stearic acid. Stearic acid and zinc oxide are almost always used together in rubber compounding. After these two ingredients are mixed in the rubber stock, they react with each other to solubilize the zinc (ion) into the rubber so that it will initiate the vulcanization process. 

Materials. Natural rubber (NR) was kindly supplied by Malaysian Rubber (Berhad, Malaysia) under the trade name CV60 (Mooney viscosity ML(1 + 4) 100 °C = 60). The compounding ingredients were all commercial grades and were added to the rubber. The curing system employed expressed as parts per hundred parts of rubber (phr) was sulphur (2.5), zinc oxide (5), stearic acid (1) and MBTS (benzothyazyl disulfide) (1). 

This section gives a brief description of other common compounding ingredients such as stearic acid and derivatives, resins, processing aids, and blowing agents. 

Some compounding ingredients tend to be included out of habit. Stearic acid is such an ingredient. Little is published and it is suspected that little is known about the influence... 

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